Rotary hammer power tool

ABSTRACT

A gear type drive train from the motor rotates a barrel, the latter having a drive formation in one end thereof configured to impart rotation to the shank of a tool element received therein. The gear train reciprocates a cylinder simultaneously with rotation of the barrel, which cylinder is reciprocally mounted within the barrel. A hammer is freely mounted within the cylinder and is pneumatically reciprocated for imparting hammering blows to a tappet mounted in the barrel between the hammer and the distal end of the tool element thereby in turn to impart hammering blows to the latter. A spring biases the tappet against the tool shank thereby to prevent flutter of the former. The rotary drive to the barrel may be selectively disconnected by a manually operated mechanism. A wall of the tool housing cooperates with the barrel to define an annular chamber for receiving a supply of grease; apertures are provided in the barrel and in the sleeve thereby permitting the grease to enter the barrel as well as the sleeve for lubricating the latter and the hammer.

llnited States Patent [1 1 Consoli et al.

[ ROTARY HAMMER POWER TOOL [75] Inventors: Frank J. Consoli, Des Plaines; Peter G. Rebechini, Aurora; Hanspeter E. Beisch, Buffalo Grove, all of Ill.

[73] Assignee: Skil Corporation, Chicago, Ill. [22] Filed: Feb. 26, 1973 [21] Appl. No.: 335,933

[52] US. Cl 173/48, 173/109, 173/118, 173/170, 173/D1G. 3, 192/89 A, 192/67 R [51] Int. Cl B25d 11/00 [58] Field of Search 173/109-111, 173/116, 117, DIG. 3, 48; 192/89 A, 67 R; 74/22 R [56] References Cited UNITED STATES PATENTS 3,334,694 8/1967 Schnettler 173/109 3,376,939 4/1968 Holzapfel 173/116 3,430,708 3/1969 Miller 1 173/109 3,463,246 8/1969 Bronnert 173/110 X 3,630,293 12/1971 Moores, Jr 173/D1G. 3 3,741,317 6/1973 U nterschweiger 173/109 [4 1 Sept. 24, 1974 Primary Examiner-John E. Murtagh Assistant Examiner-William F. Pate, lll Attorney, Agent, or Firm-McDougall, Hersh & Scott [5 7] ABSTRACT A gear type drive train from the motor rotates a barrel, the latter having a drive formation in one end thereof configured to impart rotation to the shank of a tool element received therein. The gear train reciprocates a cylinder simultaneously with rotation of the barrel, which cylinder is reciprocally mounted within the barrel. A hammer is freely mounted within the cylinder and is pneumatically reciprocated for imparting hammering blows to a tappet mounted in the barrel between the hammer and the distal end of the tool ele ment thereby in turn to impart hammering blows to the latter. A spring biases the tappet against the tool shank thereby to prevent flutter of the former. The rotary drive to the barrel may, be selectively disconnected by a manually operated mechanism. A wall of the tool housing cooperates with the barrel to define an annular chamber for receiving a supply of grease; apertures are provided in the barrel and in the sleeve thereby permitting the grease to enter the barrel as well as the sleeve for lubricating the latter and the hammer.

3 Claims, 5 Drawing Figures 1 ROTARY HAMMER POWER TOOL BACKGROUND OF THE INVENTION 1. Field of the Invention The field of the invention relates to portable power tools. More particularly, the field of the present invention relates to so-called rotary hammer power tools, i.e., power tools which have the capability of imparting simultaneous rotation and axial hammering blows to a tool element for working on concrete, for example.

2. The Prior Art Rotary hammer power tools of the type referred to are well known in the art. These tools are usually powered by an electric or pneumatic motor and include a rotary output or drive member having a hexagonal bore for receiving the correspondingly shaped shank of a tool element or adapter thereby to impart rotation to the latter. These tools include a hammering mechanism in the form of a reciprocal hammer arranged to strike the distal end of the shank of the tool element or adapter thereby to impart axial hammering blows to the latter simultaneously with the aforementioned rotation. Representative prior art tools are shown in Coates US. Pat. No. 1,191,948, Paule US. Pat. No. 3,456,740, Naslund et al. US. Pat. No. 3,114,423, McCloud US. Pat. No. 3,1 14,421 and Bassett et al. US. Pat. No. 3,270,821, the Naslund et al. McCloud and Bassett et al. patents being assigned to the assignee of the present invention.

In the use of power tools of the type under consideration, it is often required or at least desirable at certain times to impart a hammering action only to the tool ele ment or adapter or to impart rotation only to the tool element. When using the power tools shown in some of the aforementioned patents, these different modes of operation are brought about by removing the element or adapter and replacing the same with a different element or adapter. In other words, these power tools are provided with plural different tool elements each specially configured to cooperate with the hammering and rotarycomponents of the power tool for bringing about the desired mode of operation.

In some uses of these rotary hammer power tools, it is too time consuming for the operator to stop the tool, remove the tool element and insert a different too] element to achieve a different mode of operation. For example, when installing certain anchors in concrete structures, it is necessary first to hammer the anchor thereby to penetrate the concrete a short distance, and thereafter to impart simultaneous hammering and rotation to the anchor. Then, rotation only must be imparted to the anchor for removing the same in order to evacuate dust from the bore formed in the concrete. Finally, the anchormust be hammered in place without rotation. This operation could not be achieved economically and expeditiously if the operator were required to change the tool element each time to bring about the various modes of operation just described.

SUMMARY AND OBJECTS OF THE INVENTION A primary object of the present invention is the provision of a rotary hammer power tool having new and improved means for imparting simultaneous rotation and hammering blows to a tool element or adapter.

Another object of the present invention is the provision of a power tool of the type described which includes a tappet disposed between the hammer and the distal end of the shank of the tool element thereby to transfer hammering blows from the hammer to the tool element, wherein a spring is provided for biasing the tappet against the tool element thereby to prevent flutter of the tappet.

Still another object of the present invention is the provision of such a power tool wherein the mass of the tappet is substantially less than the mass of the hammer.

Another object of the present invention is the provision of a power tool of the type under consideration which includes a manually operated rotary disconnect means whereby the operator of the tool may quickly and easily change the modes of operation from simultaneous hammering and rotation to hammering only and vice versa.

Still another object of the present invention is the provision of a power tool of the type described which includes a rotating barrel having a cylinder reciprocating therein, and a hammer pneumatically reciprocating in the cylinder, wherein a wall of the power tool cooperates with the barrel to define an annular chamber adapted to contain a supply of grease, the barrel and the cylinder being provided with apertures to permit the grease to enter the barrel as well as the cylinder for lubricating the latter and the hammer.

These and other objects and advantages of the present invention will become apparent from the following specification disclosing a preferred embodiment shown in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a rotary hammer power tool embodying the present invention;

FIG. 2 is an enlarged fragmentary vertical section of the power tool;

FIG. 3 is a developed plan view of the clutch teeth forming part of the rotary disconnect of the barrel;

FIG. 4 is an enlarged vertical section of the power tool; and

FIG. 5 is an enlarged section similar to FIG. 4 showing the various parts in their position when a hammering blow is being imparted to the tool element via the spring biased tappet.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring particularly. to FIG. 1, the portable rotary hammer power tool, generally designated 10, includes a main housing 11 and a motor housing 12. Although the power tool could be pneumatically operated, it will I be understood that the power tool 10 includes a suitable electric motor vertically disposed within the housing 12 and arranged to be energized upon depressing the trigger 13 mounted by a handle 14. An auxiliary handle 15 is mounted on theforward portion of the housing 11.

A barrel 18 is rotatably mounted within the housing 11 by means of a forward ball bearing assembly 19 and a rearward ball bearing assembly 20. A rotary drive formation 22 is fixedly mounted. in the forward end of the barrel for rotation in unison therewith. This formation includes a through central bore 23 of hexagonal cross section for receiving the correspondingly shaped shank 25 of a tool element or adapter. Thus, rotation of the barrel 18 will impart corresponding rotation to the tool element by reason of the hexagonal shape of the bore 23 and shank 25.

A first sleeve 27 is mounted on the barrel 18 and is splined thereto such that the sleeve may slide axially relative to the barrel. By reason of this spline type of connection, rotation of the sleeve 27 will of course cause rotation of the barrel 18. A coil spring 28 encircles the barrel and has one end thereof in abutting engagement with the forward end of the sleeve 27. The other end of this spring engages a ring 29a, which ring abuts another ring 29, the latter being received within an annular recess 30 formed in the outer surface of the barrel 18. The spring 28 acts to urge the sleeve 27 rearwardly or inwardly (to the left as shown in the draw ings) for purposes which will become apparent hereinbelow.

Another sleeve 32 is mounted on the barrel 18 for rotation with and relative to the barrel. As best noted in FIG. 4, the sleeve 32 is interposed between the ball bearing assembly and the barrel 18. The sleeve 32 includes an integral formation of clutch teeth 33 at the forward end thereof, which teeth are arranged for engagement with an identical and opposite hand series of clutch teeth 34 formed on the inner end of the sleeve 27.

Reference should now be had to FIG. 3 showing a developed view of these clutch teeth. The set of clutch teeth 33 on the sleeve 32 are in the form of plural teeth 33a, the arcuate distance between adjacent teeth being substantially greater than the arcuate extent of each tooth. In like manner, the set of teeth 34 are in the form of individual teeth 34a, again, the open space between adjacent teeth having an arcuate extent substantially greater than the arcuate extent of each tooth. The provision of having these spaces between adjacent teeth substantially greater than the width of each tooth facilitates the engagement of the teeth when the sleeve 32 is rotating.

It will be apparent that the spring 28 urges the sleeve 27 inwardly so as to maintain the clutch teeth 33, 34 in meshing engagement. The sleeve 27 may be moved axially forwardly relative to the barrel 18 by means of a manually operated shift lever 36. This lever is suitably rotatably mounted in a bore 37 formed in the housing 11 of the power tool, and carries a pin 38 eccentric with respect to the axis of rotation of the shift lever. The pin 38 engages a flange 39 integral with the sleeve 27. It will be understood that rotation of the shift lever 36 in one direction will serve to move the sleeve forwardly against the force of the spring 28 to disengage the clutch teeth 33, 34. Rotation of the shift lever 36 in the other direction will allow the spring 28 to return the sleeve 27 to its innermost position thereby bringing the clutch teeth 33, 34 into engagement. Preferably, the shift lever includes a detent ball 40 biased by a spring 41 thereby releasably to hold the shift lever 36 in its two positions corresponding to the engaged and disengaged positions of the sleeve 27.

The sleeve 32 includes an integral formation of gear teeth 44 at one end thereof, these teeth being in meshing engagement with a gear 45 integral with a shaft 46. The shaft 46 is driven by a gear 47, this gear being in meshing engagement with teeth 48 integral with a crank shaft 49. A gear 50 is keyed to the crank shaft 49, which gear is driven by the shaft 51 of an electric motor 52 contained within the housing 12.

A cylinder 55 is mounted within the barrel 18. To this end, the cylinder 55 includes an annular formation 55a at its forward end and another annular formation 55b at its rearward end, these formations being in sliding engagement with the barrel and defining an annular space 56 between the barrel and the cylinder. A block 57 is fixedly mounted within the inner end of the cylinder 55. This block has a recess 58 receiving one end of a connecting rod 59, the latter being secured to the block 57 by means of a pin 60. The connecting rod is secured to a pin 49a by means of a roller hearing assembly 62. Of course, the pin 49a forms part of the crank shaft 49. Thus, it will be apparent that the cylinder 55 will be reciprocated within the barrel 18 simultaneously with rotation of the sleeve 32.

A cylindrical hammer 64 is mounted within the cylinder 55 for free reciprocal movement therein. The hammer 64 includes a reduced-in-diameter cylindrical formation 64b, the distal end of the latter being slidably received within a reduced-in-diameter portion 55c of the cylinder 55. It will be understood that the hammer 64 is pneumatically actuated or reciprocated in response to reciprocation of the cylinder 55. To this end, the cylinder 55 includes apertures 65 in the walls thereof for admitting a supply of air to the space 66 between the block 57 and the hammer 64. This type of pneumatic hammering operation is well known in the art and therefore requires no further discussion herein.

The barrel 18 includes an integral, annular flange 68 intermediate the ends thereof. A coil spring 69 has one end thereof in abutting engagement with a washer 70, the latter being held against the annular flange 68 by the spring 69. The other end of this spring is engaged with a tappet 72 for urging the latter forwardly in the barrel 18. The tappet 72 includes an exterior annular recess 73 which receives a ring 74. It will be understood that the tappet 72 is mounted for reciprocal sliding movement within the barrel 18.

When a tool element is not in place, as shown in FIG. 2, the spring 69 urges the tappet 72 forwardly and into abutting engagement with an annular face 22a on the inner end of the drive formation 22. When a tool element is mounted in the power tool, the distal end of the former engages thetappet 72 and moves the same inwardly against the force of the spring 69. The hammer extension 64b strikes the tappet 72 (FIG. 5) and thus hammering blows are imparted to the tool element when the distal end of the shank 25 is in abutting engagement with the tappet. In other words, opposite faces of the tappet are arranged to be engaged by the respective distal ends of the shank 25 and the hammer extension 6412 thereby to transfer hammering blows from the hammer to the tool element. The spring 69 acts to prevent fluttering or unwanted axial reciprocal movement of the tappet during operation of the power tool. Also, this unwanted fluttering action is avoided by having the mass of the tappet 72 substantially less than the mass of the hammer 64.

The housing 11 includes a wall portion 11a which cooperates with the barrel 18 to define an annular space or chamber 76; the forwardmost extremity of this chamber is defined by an annular flange 77 integral with the housing 11. A frusto-conical member 78 forms a seal between the flange 77 and the barrel 18. This seal is held in place by the ring 29 on the barrel 18.

The annular space 76 communicates with the crank case chamber 80 via the openings between the individual ball bearings of the ball bearing assembly 20. It will be understood that the spaces 76 and 80 contain a supply of highly viscous lubricating composition, such as a suitable type of grease. The barrel 18 includes plural apertures 82 thereby to permit the grease to enter the barrel and lubricate the walls thereof. The grease passing through the apertures 82 will enter the annular space 56 between the cylinder 55 and the barrel l8 and will in turn enter the barrel through the openings 65. Accordingly, the supply of grease from the space 76 will also lubricate the surfaces of the sleeve and hammer which engage each other.

The power tool 11 includes a plate 84 removably secured thereto as by means of fasteners 85. The plate 84 may be removed from time to time to replenish the supply of grease. Under some conditions, it may be desirable to replace the ball bearing assembly by a sintered type annular bearing which would not permit grease from the chamber 80 to pass to the annular chamber 76. In the event such a bearing assembly is used for the sleeve 32, suitable means, such as a cap or removable plate, will be provided in the housing wall 11a to replenish the supply of grease in the chamber 76 from time to time.

It will be apparent that the present invention provides a new and improved rotary hammer power tool for imparting simultaneous hammering and rotation to a tool element or adapter. if it is desired to convert from simultaneous hammering and rotation to hammering only, the shift lever 36 may be actuated to disengage the clutch teeth 33, 34. The simultaneous hammering and rotation mode of operation may be quickly resumed, again by actuation of the shift lever 36; this operation may be achieved even when the tool is in operation, i.e., with the sleeve 32 rotating. If it is desired to achieve rotation only, the tool may be withdrawn from the work which will result in the drive member 23 being moved axially relative to the shank 25 thereby allowing the tappet 72 to come to rest against the annular face 22a. The tappet will now be beyond the range of reciprocal movement of the hammer 64 and rotation only will be imparted to the tool element, provided the shift lever 36 is positioned for bringing about engagement of the clutch teeth 33, 34.

We claim:

1. In a portable power tool of the type adapted to impart rotation and hammering blows simultaneously to an elongated tool element having a shank atone end thereof, the improvement comprising:

a. a barrel rotatably mounted in the housing of the power tool; 7

b. a rotary drive formation secured to said barrel at one end thereof for engaging the shank of a tool element when the latter is received in said one end of the barrel thereby to impart rotation to the tool element in response to rotation of the barrel;

c. motor means in said housing; I

d. a cylinder coaxial with said barrel and slidably mounted in the latter adjacent the other end thereof for axial reciprocal movement therein;

e. a drive train connecting said cylinder with said motor such that the former is reciprocated upon operation of the latter;

f. a cylindrical hammer coaxially disposed within said barrel and mounted therein for pneumatic, reciprocal hammering movement in response to reciprocation of said cylinder, which hammer has a formation arranged to transmit hammering blows to the distal end of said shank;

g. a first sleeve coaxially mounted on said barrel for rotation with and relative to the barrel, said first sleeve including a first set of clutch teeth at one end thereof;

h. said drive train including gear means on the other end of said first sleeve connecting said first sleeve with said motor means for rotation of the former upon operation of the latter;

. a second sleeve coaxially mounted on said barrel for reciprocal, axial sliding movement relative thereto, which second sleeve is connected to said barrel for imparting rotation thereto, said second sleeve mounting a second set of clutch teeth at one end thereof and arranged for engagement with said first clutch teeth; and

j. selector means mounted on the housing of the power tool and engaged with said second sleeve for reciprocating the latter axially thereby to engage and disengage said first and second clutch teeth for selective rotation of said barrel.

2. The improvement according to claim 1 wherein said first and second sets of clutch teeth are substantially identical and opposite hand versions of each other, each set of clutch teeth being in the form of a plurality of individual teeth arranged in circumferential spaced relation, the open space between adjacent teeth having an arcuate extent substantially greater than the arcuate extent of each tooth thereby to facilitate the engagement of said first and second sets of clutch teeth at times when said first cylindrical formation is rotating.

3. In a portable power tool of the type adapted to impart rotation and hammering blows simultaneously to an elongated tool element having a shank at one end thereof, the improvement comprising:

a. a barrel rotatably mounted in the housing of the power tool;

b. a rotary drive formation secured to the barrel at one end thereof for engaging the shank of a tool element when the latter is received at one end of the barrel thereby to impart rotation to the tool element in response to rotation of the barrel;

c. gear means connected to said barrel adjacent the other end thereof for rotation of the barrel in response to rotation of the gear means;

d. motor means in said housing including a drive train engaged with said gear means thereby to impart powered rotation thereto;

e. a cylinder coaxial with said barrel and, slidably mounted in the latter adjacent said other end thereof for axial reciprocal movement therein;

f. said drive train including means engaged with said cylinder at one end thereof for reciprocating the same simultaneously with rotation of said gear means;

g. a cylindrical hammer coaxial with said cylinder and freely mounted therein for pneumatic, reciprocal hammering movement in'response to reciprocation of said cylinder, which hammer has a coaxial extension arranged to project beyond, and outwardly of the other end of said cylinder when the latter is in the forward portion of its stroke, which extension is arranged to transmit hammering blows to the distal end of the shank of the tool element;

position, which seal means includes an annular seal engaging said wall means and said barrel to form a seal therebetween, said annular seal defining the forward limit of said annular space; and

said barrel and said cylinder each having apertures in the walls thereof thereby permitting the aforesaid lubricating composition to enter the barrel and said cylinder thereby to lubricate the cylinder and the hammer. 

1. In a portable power tool of the type adapted to impart rotation and hammering blows simultaneously to an elongated tool element having a shank at one end thereof, the improvement comprising: a. a barrel rotatably mounted in the housing of the power tool; b. a rotary drive formation secured to said barrel at one end thereof for engaging the shank of a tool element when the latter is received in said one end of the barrel thereby to impart rotation to the tool element in response to rotation of the barrel; c. motor means in said housing; d. a cylinder coaxial with said barrel and slidably mounted in the latter adjacent the other end thereof for axial reciprocal movement therein; e. a drive train connecting said cylinder with said motor such that the former is reciprocated upon operation of the latter; f. a cylindrical hammer coaxially disposed within said barrel and mounted therein for pneumatic, reciprocal hammering movement in response to reciprocation of said cylinder, which hammer has a formation arranged to transmit hammering blows to the distal end of said shank; g. a first sleeve coaxially mounted on said barrel for rotation with and relative to the barrel, said first sleeve including a first set of clutch teeth at one end thereof; h. said drive train including gear means on the other end of said first sleeve connecting said first sleeve with said motor means for rotation of the former upon operation of the latter; i. a second sleeve coaxially mounted on said barrel for reciprocal, axial sliding movement relative thereto, which second sleeve is connected to said barrel for imparting rotation thereto, said second sleeve mounting a second set of clutch teeth at one end thereof and arranged for engagement with said first clutch teeth; and j. selector means mounted on the housing of the power tool and engaged with said second sleeve for reciprocating the latter axially thereby to engage and disengage said first and second clutch teeth for selective rotation of said barrel.
 2. The improvement according to claim 1 wherein said first and second sets of clutch teeth are substantially identical and opposite hand versions of each other, each set of clutch teeth being in the form of a plurality of individual teeth arranged in circumferential spaced relation, the open space between adjacent tEeth having an arcuate extent substantially greater than the arcuate extent of each tooth thereby to facilitate the engagement of said first and second sets of clutch teeth at times when said first cylindrical formation is rotating.
 3. In a portable power tool of the type adapted to impart rotation and hammering blows simultaneously to an elongated tool element having a shank at one end thereof, the improvement comprising: a. a barrel rotatably mounted in the housing of the power tool; b. a rotary drive formation secured to the barrel at one end thereof for engaging the shank of a tool element when the latter is received at one end of the barrel thereby to impart rotation to the tool element in response to rotation of the barrel; c. gear means connected to said barrel adjacent the other end thereof for rotation of the barrel in response to rotation of the gear means; d. motor means in said housing including a drive train engaged with said gear means thereby to impart powered rotation thereto; e. a cylinder coaxial with said barrel and slidably mounted in the latter adjacent said other end thereof for axial reciprocal movement therein; f. said drive train including means engaged with said cylinder at one end thereof for reciprocating the same simultaneously with rotation of said gear means; g. a cylindrical hammer coaxial with said cylinder and freely mounted therein for pneumatic, reciprocal hammering movement in response to reciprocation of said cylinder, which hammer has a coaxial extension arranged to project beyond and outwardly of the other end of said cylinder when the latter is in the forward portion of its stroke, which extension is arranged to transmit hammering blows to the distal end of the shank of the tool element; h. said housing of the power tool having wall means cooperating with said barrel to define an annular space therearound, which annular space has an axial extent substantially conterminous with the portion of said barrel in which said cylinder reciprocates; i. seal means closing said annular space from the atomsphere and adapting said annular space to contain a supply of highly viscous lubricating composition, which seal means includes an annular seal engaging said wall means and said barrel to form a seal therebetween, said annular seal defining the forward limit of said annular space; and j. said barrel and said cylinder each having apertures in the walls thereof thereby permitting the aforesaid lubricating composition to enter the barrel and said cylinder thereby to lubricate the cylinder and the hammer. 